The present invention relates to a method and apparatus for preparing hot beverages. In particular, but not exclusively, the present invention relates to a method and an associated apparatus for the preparation of a range of teas, the infusion of each type of tea being controlled in terms of water temperature and infusion time.
Different varieties of tea, for example, the three major types of tea: black tea; green tea; or oolong; require very specific brewing conditions for optimal extraction of polyphenols (tannins), theine (caffeine) and aromatic oils. Additionally, a too lengthy duration of infusion may yield a bitter taste in certain teas.
Tea leaves of different varieties may vary greatly in terms of their volumetric density and a given weight of tea leaves may therefore represent a widely variable volume of leaves and surface area which will be exposed to water during the infusion process. Lower density teas generally require a longer duration of infusion in order to provide full extraction of the flavour. Also, according to their individual characteristics, teas of different varieties require different infusion temperatures for optimal flavour extraction. Through experimentation, preferred infusion duration and temperature may be determined for the optimal preparation of a variety of fine teas. Of note, however, is that a relatively constant mass of tea leaves is required for the preparation of a given volume of tea, regardless of the type.
For instance, Gyokiro requires 2 minutes of infusion at a temperature of 50xc2x0 C. while Keemun must be infused at a temperature of 95xc2x0 C. for 3 minutes and Sencha is best prepared at a temperature of about 75xc2x0 C. for 2 minutes. Some very light white teas may require up to 12 minutes of infusion at low temperature (for example 65xc2x0 C.) for optimal taste.
In order to support the preparation of fine teas in tea rooms, tea sections of coffee shops and restaurants, a method and apparatus capable of providing high quality teas on a commercial basis is required.
A number of devices have been developed to assist in the preparation of tea, but these devices present major limitations.
For example, in U.S. Pat. No. 5,188,019, issued to Vahabpour on Feb. 23, 1993, boiling water from a reservoir is conveyed into a strainer containing the tea leaves by activation of a manually operated valve. After a user evaluated infusion time, a second manually operated flow valve can be operated to pour the prepared tea into a serving vessel, while simultaneously mixing the tea with water to reduce strength. Although the tea leaves are in contact with the hot water for an extended amount of time, the user is required to determine the proper length of time for brewing the tea.
U.S. Pat. No. 4,888,466, issued to Hoffmann on Dec. 19, 1989, discloses a machine for making hot tea in which boiling water is automatically conveyed through a riser to an infusion receptacle provided with a discharge valve at its bottom. The discharge valve can be electro-mechanically controlled so as to provide automatic discharge of the beverage into the serving vessel after a desired infusion time has elapsed. This design, however, does not provide for the selection of a desired infusion temperature and provides no indication of the appropriate infusion time for a given type of tea.
The majority of these tea preparation devices are based on a drip principle, similar to that typically used in drip-brew coffee machines, where boiling water is pumped and dispensed over a soft filter basket containing the leaves and supported into a rigid closed basket comprising an outlet at its lower end. The continuously circulating hot water extracts flavour contained in the tea leaves and exits the basket through a possibly adjustable outlet, filling a serving vessel. Although an adjustable outlet enables a user to set the time required for a volume of water to pass from the filter basket through the outlet and to the serving vessel, such a concept cannot ensure that each leaf is able to loosely float in water for the specific period of time required to optimally dissipate its flavour.
Additionally, with such a concept, infusion time varies as a function of the volume of water to flow through the outlet, which is inadequate since preparation of a larger volume of tea with the accordingly selected mass of leaves (e.g. 4 g per 225 ml of beverage) should take no longer than for a smaller volume in optimal conditions. Furthermore, the concept generally operates with boiling water, which is often too hot for optimal infusion of fine teas. U.S. Pat. No. 5,901,635 issued to Lucas et al. on May 11, 1999 and U.S. Pat. No. 4,825,758 issued to Snowball on May 2, 1989 provide examples of such automatic drip type tea brewing machine offered for commercial use.
Japanese application No JP2013693 (Murakamixe2x80x94laid open in February 1992) teaches a sophisticated tea vending machine also based on the drip principle. Nevertheless, it features the use of two or more hot water reservoirs maintained at different temperatures and from which water is selectively drawn according to the type of tea to be prepared. Once again, however, proper control of the extraction of the flavour from tea leaves can not be achieved as there is no through wetting by contact with surrounding water for a required period of time.
Another highly automated brewer intended for black tea beverage preparation is disclosed in Japanese application JP10328031 (Fugiwara), laid open on Dec. 15, 1998. The brewer provides for infusion with agitation of the leaves to promote contact with water and two infusion times depending on the leaf size (Large: 2xe2x80x230xe2x80x3 or Small; 4xe2x80x230xe2x80x3) as inputted by the user. The beverage is automatically discharged into the serving vessel when the steeping time is elapsed. The apparatus also determines from a chart and weights the quantity of leaves required as a function of the number of servings indicated by the user. It is apparent, however, that the apparatus has not been designed to provide the level of versatility required for the preparation of the three major types of tea. The principal limitation being the unique infusion water temperature set to 90xc2x0 C. and the choice from two infusion times only. Moreover, this device does not allow for the controlled re-heating of a tea infused at a low temperature or come equipped with practical commercial features, such as automatic flush cleaning of the infusion chamber and other parts coming into contact with the tea prior to preparation of a new batch of potentially different types of tea.
From the above survey of tea preparation methods and apparatuses, it is apparent that they fail to respond to the need for the automatic preparation of a wide range of fine teas according to optimal conditions as provided by the traditional methods. There is thus a need for a method and an apparatus responding to the increasing market need for automatic preparation of fine teas for use on a commercial basis in tea rooms, tea sections of coffee shops or restaurants.
The present invention relates to a method for producing a quantity of a hot beverage, comprising:
providing a source of a liquid having an adjustable temperature;
selecting an infusion time and an infusion temperature;
supplying from the source liquid substantially at the selected infusion temperature, the supplied liquid having a volume equal to or slightly larger than the quantity;
mixing the supplied liquid with a flavour ingredient having the selected infusion time and infusion temperature;
infusing the flavour ingredient in the supplied liquid substantially for the selected infusion time whereby the flavour ingredient is at least partially dissipated in the supplied liquid thereby forming a brew; and
following the infusion time, removing an undissipated portion of the flavour ingredient from the brew thereby yielding the beverage.
The present invention also relates an apparatus for producing a quantity of a hot beverage comprising:
a hot beverage production controller;
a source of a liquid having an adjustable temperature connected to the controller;
a selector of infusion time and infusion temperature connected to the controller;
a valve system interposed between the source and an infusion chamber, the valve system being connected to and controlled by the controller to supply liquid substantially at the selected infusion temperature from the source to the infusion chamber;
the infusion chamber for infusing a flavour ingredient with the liquid substantially at the selected infusion temperature substantially for the selected infusion time, wherein the infusion chamber has an outlet, the flavour ingredient has the selected infusion time and infusion temperature, and the flavour ingredient dissipates in the liquid thereby forming a brew;
a dispensing circuit interposed between the outlet of the infusion chamber and a vessel, and connected to and controlled by the controller to discharge the brew into the vessel; and
a mechanical filter disposed for removing an undissipated portion of the flavour ingredient from the brew prior to discharging it in the vessel.
The foregoing and other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof given for the purpose of illustration only with reference to the accompanying drawings.